1. Field
The following description relates to a semiconductor device, and to a multi-source junction gate field-effect transistor (JFET) device having two or more source regions to control and supply a necessary amount of electric current depending on use of an application which is in need of constant electric current supply.
2. Description of Related Art
A voltage control device such as junction gate field-effect transistor (JFET) may function as an electrically-controlled switch when operating in saturation region, while functioning as a voltage control variable resistor when operating in resistive region. The JFET thus provides ideal characteristics for use as a high-input impedance signal source or transimpedance. Further, low current noise and signal distortion characteristics are suitable for audio and high-frequency applications. However, varying input impedance according to temperature, DC performance, or voltage component noise characteristics work as limitation that deters use of JFET amplification application.
The structure of JFET providing the above-mentioned characteristics will be explained below with reference to FIG. 1. FIG. 1 is a schematic plan view of a conventional JFET.
Referring to FIG. 1, a JFET 10 includes a drain region 20 at the center, and a gate region 30 formed around the drain region 20. One source region 40, having a fixed area, is also formed outside the gate region 30.
The JFET 10 also includes a bulk region 50, and a metal 60 connected to the bulk region 50. The JFET 10 is hereinafter referred to as “single-source FET.”
The single-source FET 10 illustrated in FIG. 1 will be explained below.
Because the single-source FET 10 has one fixed source region 40, current use is limited. That is, in an application that requires LED be ON constantly, since current is supplied only via one fixed current path, it is not possible to control current amount.
Accordingly, it is necessary to connect a plurality of single-source FETs, when the application needs larger current amount than is provided by a single-source FET 10, which is quite inconvenient.
Furthermore, there is also a burden of having to fabricate new FET with different, suitable structure.